Transfer element and method of making the same



42 L408 XR 298729340 SR Feb. 3, I95 D. A. NEWMAN ETAL 2,372,349

TRANSFER ELEMENT AND METHOD OF MAKING THE SAME I Filed Feb. 18. 1954 4? 1a PRESSURE -SENSITIVE f N Y I TRA SFER LA ER W w/ FLEXIBLE EVAPORATION RES! DU E OF FOUNDATION A UNIFORM MIXTURE OF RESIN [E.G.ETI-IYL cELLuLosE] WITH MISCIBLE LIQUIDS:

I. SOLVENT OF HIGH EVAPORATION RATE 2 NON-SOLVENT or Low EVAPORATION RATE SOLID BASE O/"ozher resinous MATEfiIAL fi'Im-farmz'rgg male/"1&2 [ETHYL cELLuLosE] FLEXIBLE FOUNDATION \IQLATILE SGLVENT $HEET [E.G.CELLOPHANEJ EEG. ALCOHOL] VOLA'TILE -lessm MON-SOLVENT To an ZWMLECLWATER] MIX MAT TE powder SPREAD CGTING THIN COM ese'raow LAYER I VOLATILE off SOLVENT EVA PORATI ON VOLATILE a/f NON- SOLVENT Haw/7y proper'zz'es of .51 Transfer-054! 'z 7 Surfacesy U Allan TJM/azz/maer I L o (Ittorneg United States Patent TRANSFER ELEMENT AND METHOD OF MAKING THE SAME Douglas A. Newman, Glen Cove, and Allan T. Schlot zhauer, Locust Valley, N. Y., assignors to Columbia Ribbon & Carbon Manufacturing Company, Inc., Glen Cove, N. Y., a corporation of New York Application February 18, 1954, Serial No. 411,272

9 Claims. (Cl. 117-36) This invention relates to manifolding and more particularly to methods of making transfer members such as sheets or strips, to ink compositions or pastes for use in the production of such transfer elements, and to the novel transfer elements themselves.

Ink compositions for the above purpose heretofore employed have in general been composed of waxes and oils, together with pigment colors. Carbon papers and ribbons produced with such compositions have the disadvantage that they tend to soften excessively when sub jected to unusually high temperatures in warmer climates with resultant sticking of sheets, improper writing and allied inconveniences.

Furthermore, carbon papers and ribbons produced with compositions including wax as the solid color carrier are known to have the property of increasing in tackiness in response to pressure, with the result that the smudging of sheets during handling is difficult to control.

In connection with the type of transfer members which are intended and designed to transfer readily and substantially completely from their foundations, it often happens that the heat softening properties of a wax base layer are of special concern, for such papers would otherwise have extensive applicability for the purpose of making mechanical negatives or mechanically prepared projection slides by writing or typing. Under the circum stances, however, the tendency of the waxy material of the carbon layer to soften under heat prevents or at least severely limits such use, since the temperatures accompanying the photographic printing of a negative or the projection of a slide are often quite high and, if excessive, destroy the negative or slide.

According to the present invention new carriers or solid bases for pigments for use in the production of carbon papers and the like have been discovered, that is to say, a process has been discovered whereby certain film-forming materials, heretofore considered as unsuitable as the base for pressure transfer layers designed for pressure operation alone, can be rendered pressure transferrable and hence useful in this connection. This invention has for an object, therefore, the manufacture of transfer or carbon paper sheets having thereon a transfer or carbon composition including a solid base material which, in its usual form, is normally considered not to be pressure transferable, the making of such compositions, and the development of a method to this end.

Those film-forming plastics which are highly cohesive, and which tend to have more cohesion than surface adhesion for other materials or articles when dry, are the primary subject matter of this invention. Such materials are the usual resinous binders such as are used in lacquers and the like, and which are generally considered inappropriate as the solid base material for carbon paper coatings, which need to be pressure transferrable. According to the present invention, it has been discovered that these resinous materials can be temporarily broken down or altered in their physical properties so as to have an apparent reduction in their cohesive properties, giving a relative increase in the ratio of adhesion to cohesion which in most cases will render them pressure transferrable.

Additional objects, features and advantages will appear hereinafter as the description proceeds.

In the drawing,

Figure 1 is a diagrammatic section to a large scale illustrating a pressure-sensitive transfer sheet according to the present invention.

Fig. 2 is a flow sheet of the process for making the transfer sheet of Fig. 1.

Referring to the drawing, Fig. 1 illustrates a transfer sheet made according to the present invention and including a flexible foundation 11 on which is formed a pressure-sensitive transfer layer 13. Whereas the layer 13 has heretofore been usually compounded of waxes and oils, the present invention relates to a layer essentially of a resinous material such as ethyl cellulose, the physical properties of which have been altered to render it pressure-transferable.

The alteration in physical properties can be brought about, it has been discovered, by properly selecting and adjusting the suspending liquids during coating. At least two different liquids are used to form the continuous phase of the dispersion, one being a solvent for the solid base material, and the other being, at least by comparison, substantially a non-solvent therefor at ordinary working temperatures. Both liquids are of a volatile nature to the extent that they can be driven off" from the cast coating by evaporation. In most instances, although not necessarily in all, the non-solvent liquid is water and has an evaporation rate substantially lower than that of the solvent. The liquids used must be miscible or at least capable in some fashion of forming a stable substantially homogeneous admixture so that both will be well and uniformly distributed throughout any coating paste in which they are used. The solvent liquid is usually an organic solvent having a fairly high evaporation rate, and is generally used in amounts substantially in excess of the amount of non-solvent liquid present. In the case of mixtures which use water as the non-solvent liquid, it is convenient to use any of various alcohols as the solvent due to their miscibility with water.

The solid base material is selected so as to be soluble in that portion of the liquid which is regarded as the solvent, i. e., in the alcohol in the instance noted. An example of a cellulose plastic which can be employed with the alcohol-water mixture suggested above is a cellulose ether such as ethyl cellulose.

The mixture of solid base material and liquids is colored by the admixture of suitable pigments and/or dyes in proper proportions to produce the appearance or hue desired. While a wide variety of pigments and dyes may be used, especially good results have thus far been obtained using pigments of a non-porous and non-absorptive character, e. g., metal powders, known in the art as bronze powders, and these are at present preferred.

An example of a coating mixture made according to the present invention and one which is presently preferred is given by the following formula:

Ingredients: Parts by weight Ethyl cellulose (low viscosity) 50 Methanol 453 Water 44 Bronze powder 171 The proportions shown are intended to be illustrative only and not necessarily limiting. For example, the amount of ethyl cellulose for a total of approximately 500 parts of liquid may vary between and 55 parts, depending upon the viscosity desired for the coating method to be used. The proportion of parts has been found to be the most convenient under ordinary circumstances. The softness or hardness of the resulting transfer layer can be controlled by varying the amount of non-solvent, in this case water, and in the example given the amount of water used may vary between 25 parts and 75 parts to achieve the desired texture in the resulting transfer layer.

The ingredients of the mixture set forth in the foregoing example are thoroughly intermixed, for example, by grinding in a ball mill. The resulting paste or carbon ink is spread in a thin, uniform coating 13 on a flexible foundation 11 and allowed to dry by evaporation of the liquid constituents to form a pressure-sensitive transfer or carbon sheet 7;

The operation of mixtures of this character is not exactly understood at present, but it is thought that the solid base, ethyl cellulose in the foregoing example, by

being dissolved in the solvent (methanol) has the miscible but non-solvent liquid (water) thoroughly distributed through itself. As the coating begins to dry, it appears that the solvent, in evaporating more rapidly, forms a matrix of partially solidified base material which has become firm enough to hold its shape, but which is interrnpted by water particles infinitesimal in size. As the evaporation proceeds to completion the base material loses most of the solvent and eventually most of the nonsolvent liquid particles so that it acquires a loosely knit honeycomb structure differing substantially in physical properties from the ordinary plasticized lacquer or wax coating.

When a transfer sheet 7 formed as described above is placed in contact with a copy-receiving surface and printing or writing pressure is applied thereto, it is found that the coating 13 transfers readily from the foundation sheet 11 to the copy surface, making a sharp, legible mark thereon.

Carbon papers coated with compositions according to the present invention are thoroughly resistant to heat softening in all climates. They are also free of any tendency toward increased tackiness under pressure and hence will be noticeably cleaner handling than when waxbase transfer films are used. Carbon papers produced with the compositions of the present invention are free of rancidity-producing substances and do not dry out over long periods of time and hence have excellent storage qualities.

It has also been discovered that the carbon compositions of the present invention have the surprising property of being efiectively received and held by non-absorbent and glossy surfaces. They can accordingly be carried by such foundations as cellophane or glassine paper without requiring preliminary preparation of the surface and can be transferred by pressure from any suitable foundation 11 to such normally unreceptive surfaces as glass or smooth cellulose acetate sheet. Hence mechanical negatives or positives for photographic purposes may be produced with facility.

If the mechanical negative thus formed, or the positive on the copy-receiving surface, is subjected to high temperatures as would be required by the making of a photographic print or the projection of a slide, no injury will be done and the piece can be used over and over again under such conditions.

While the invention has been particularly described in connection with the use of pigments for ordinary carbon paper use, it will be understood that the formula may be revised to include suitable proportions of soluble dyes which will give to the coating hectographic properties and that pressure-inscribed copies from such a sheet may be used as masters for producing hectographic copies by the known spirit or gelatin methods.

According to the present invention the transfer coating may be applied to a physically separate sheet to be positioned between two copy sheets or it may be applied to the back of a copy sheet in certain areas in the form of spots or over the entire working area of the sheet. Ordinarily, however, the back coating of a copy or record sheet with transferable material such as carbon is objectionable since it easily soils the hands or anything coming in rubbing contact with it. This objection is overcome by the present invention by applying over the carbon coated area of the work sheet a coating of the transfer material of the present invention in which white or light-colored pigments are incorporated instead of the carbon or dark-colored pigments. Thus the appearance of the record or copy sheet is enhanced and soiling by casual rubbing contact is avoided because the overcoating does not contain marking material and because of its nature does not transfer easily unless under writing pressure or impact.

As in the base coating first referred to above the overcoating is so adjusted that when applied and dried it becomes frangible so as to break down and transfer to the underlying copy sheet along with the base coating pigment and/or dye on the sheet.

The nndercoating may be formulated as indicated above or it may be of any suitable composition including those commonly employed for carbon or hectographic ink coatings. The overcoating may be made according to the formula given above but using aluminum powder or titanium or other relatively opaque light-colored pigment.

Variations and modifications may be made within the scope of the claims and portions of the improvements may be used without others.

We claim:

1. The method of making a transfer member sensitive to writing or typing pressure which comprises uniformly dispersing an essentially cohesive film-forming cellulose ether plastic in a liquid medium made up of two significant miscible uniformly intermixed volatile fractions, one fraction being a lower alkyl alcohol which is a rapidly evaporating solvent for the plastic and the other fraction being water, miscible with and being less rapidly evapo rating than said first-named fraction and substantially a non-solvent for said plastic under normal conditions, the ratio of alcohol to water being between 5:1 and 20:1 by weight; spreading the uniform dispersion as a thin uniform coating on a flexible foundation; and evaporating the liquid medium to form a pressure-transferable layer.

2. The method of making a transfer member sensitive to writing or typing pressure which comprises uniformly dispersing ethyl cellulose in a liquid medium made up of a major fraction of a rapidly evaporating volatile alcohol in which the ethyl cellulose is soluble, and a minor fraction of from about /5 to about by weight of the alcohol being water intimately intermixed therewith; spreading the uniform dispersion as a thin uniform coating on a flexible foundation; and evaporating the liquid medium to form a pressure-transferable layer.

3. The method of making a transfer member sensitive to writing or typing pressure which comprises uniformly dispersing ethyl cellulose in a liquid medium made up of a rapidly evaporating volatile alcohol in which the ethyl cellulose is soluble. and water in the ratio by weight of about 5:1 and intimately intermixed; spreading the uniform dispersion as a thin uniform coating on a flexible foundation; and evaporating the liquid medium to form a pressure-transferable layer.

4. The method of making a transfer member sensitive to writing or typing pressure which comprises uniformly dispersing a non-absorptive pigment and an essentially cohesive ethyl cellulose plastic of low viscosity in a liquid medium made up of two significant intimately mixed miscible volatile fractions having different evaporation rates, a major fraction being a lower aliphatic alcohol which is a solvent for the plastic and having a rapid evaporation rate and the other fraction being water, miscible with the alcohol and being substantially a nonsolvent for said plastic under normal conditions and having a lesser evaporation rate than the alcohol, the ratio of the alcohol to water being between 5:1 and 20:1 by weight; spreading the uniform dispersion as a thin uniform coating on a flexible foundation; and evaporating the liquid medium to form a pressure-transferable layer.

5. The method of making a transfer member sensitive to writing or typing pressure which comprises uniformly dispersing bronze powder and ethyl cellulose in a liquid medium made up of a rapidly evaporating volatile alcohol in which the ethyl cellulose is soluble, and water in the ratio of weight of about 5:1 and intimately intermixed; spreading the uniform dispersion as a thin uniform coating on a flexible foundation; and evaporating the liquid medium to form a pressure-transferable layer.

6. The method of making a transfer member sensitive to writing or typing pressure which comprises uniformly dispersing hectograph dye and ethyl cellulose in a liquid medium made up of a rapidly evaporating volatile alcohol in which the ethyl cellulose is soluble, and water in the ratio by weight of about 5:1 and uniformly mixed; spreading the uniform dispersion as a thin uniform coating on a flexible foundation; and evaporating the liquid medium to form a pressure-transferable layer.

7. The method of making a transfer member which comprises uniformly dispersing an essentially cohesive ethyl cellulose plastic of low viscosity in a liquid medium made up of two significant miscible uniformly mixed volatile fractions, one fraction being a lower aliphatic alcohol which is a rapidly evaporating solvent for the plastic, and the other fraction being water, miscible with the alcohol and being less rapidly evaporating than the alcohol and substantially a non-solvent for the plastic under normal conditions, the ratio of alcohol to water being between 5:1 and 20:1 by weight; spreading the uniform dispersion as a thin uniform coating over a color-carrying transfer coating on a flexible foundation; and evaporating the liquid medium to form a protective coating over said color-carrying coating and pressuretransferable with the latter.

8. As a new article of manufacture a transfer member prepared in accordance with the method of claim 1, said layer being of a loosely knit honeycombed structure and having greater inherent cohesion than it has adhesion to its supporting flexible foundation while having greater adhesion under pressure to a copy-receiving member than to said flexible foundation whereby said layer is locally transferable by said pressure to a copy-receiving member and adheres thereto.

9. As a new article of manufacture a transfer member prepared in accordance with the method of claim 7, said protective coating being of a loosely knit honeycombed structure and having greater inherent cohesion than it has adhesion to its supporting flexible foundation while having greater adhesion under pressure to a copy-receiving member than to said flexible foundation whereby said protective coating is locally transferable by said pressure to a copy-receiving member and adheres thereto.

References Cited in the file of this patent OTHER REFERENCES Lacquer Emulsion, Hercules I, Powder Company, Wilmington, Del. (1945 Ethyle Cellulose, Hercules II, Powder Company, Wilmington, Del. (1949). (Copy in Div. 63.)

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No,, 2,872,340 February 3, 1959 J Douglas A, Newman et aln It is herebfi certified that error appears in the -printed specification of the above "numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 5, line 15, for of", first occurrence, read me by column 6, line 27, list of references cited, under the heading "UNITED STATES PATENTSW for "Mar, 6, 1952 read me Mar, 6;, 1951 line 33, under the heading "FOREIGN PAITEIQTRS for "Jana 4, 1955" read fie May 22;, 1935 line 38, under the heading "OTHER REFERENOES% for "'Ethyle ellulos'e, read me Ethyl Cellulose Signed and sealed this 2nd day of June 195% (SEAL) Attest: KARL AXLINE ROBERT C. WATSON Attesting Officer Commissioner of Patents 

1. THE METHOD OF MAKING A TRANSFER MEMBER SENSITIVE TO WRITING OR TYPING PRESSURE WHICH COMPRISES UNIFORMLY DISPERSING AN ESSENTIALLY COHESIVE FILM-FORMING CELLULOSE ETHER PLASTIC IN A LIQUID MEDIUM MADE UP OF TWO SIGNIFICANT MISCIBLE UNIFORMLY INTERMIXED VOLATILE FRACTIONS, ONE FRACTION BEING A LOWER ALKYL ALCOHOL WHICH IS A RAPIDLY EVAPORATING SOLVENT FOR THE PLASTIC AND THE OTHER FRACTION BEING WATER, MISCIBLE WITH AND BEING LESS RAPIDLY EVAPRATING THAN SAID FIRST-NAMED FRACTION AND SUBSTANTIALLY A NON-SOLVENT FOR SAID PLASTIC UNDER NORMAL CONDITIONS, THE RATIO OF ALCOHOL TO WATER BEING BETWEEN 5:1 AND 20:1 BY WEIGHT; SPREADING THE UNIFORM DISPERSION AS A THIN UNIFORM COATING ON A FLEXIBLE FOUNDATION; AND EVAPORATING THE LIQUID MEDIUM TO FORM A RESSURE-TRANSFERABLE LAYER. 